Loans, Allowance for Credit Losses and Credit Quality - Financing Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		$ 159,131	$ 144,518	$ 152,419	$ 146,922
Charge-offs			(544)	(24,582)	(1,250)
Recoveries			345	560	647
Provision for (release of) credit losses		5,000	0	12,250	(2,000)
Ending balance	[1]	140,647	144,319	140,647	144,319
Allowance for Loan and Lease Losses, Write-offs		(23,767)		(24,582)
Allowance for Loan and Lease Loss, Recovery of Bad Debts		283
Provision for Loan and Lease Losses		5,000
Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		36,932	14,169	27,559	14,402
Charge-offs			0	(23,471)	0
Recoveries			29	21	42
Provision for (release of) credit losses			(91)	11,033	(337)
Ending balance	[1]	15,142	14,107	15,142	14,107
Allowance for Loan and Lease Losses, Write-offs		(23,190)		(23,471)
Allowance for Loan and Lease Loss, Recovery of Bad Debts		16
Provision for Loan and Lease Losses		1,384
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		76,198	84,436	77,799	83,486
Charge-offs			0	0	0
Recoveries			0	0	3
Provision for (release of) credit losses			(980)	597	(33)
Ending balance	[1]	78,396	83,456	78,396	83,456
Allowance for Loan and Lease Losses, Write-offs		0		0
Allowance for Loan and Lease Loss, Recovery of Bad Debts		0
Provision for Loan and Lease Losses		2,198
Construction Loans [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		9,248	11,867	10,762	12,316
Charge-offs			0	0	0
Recoveries			0	0	0
Provision for (release of) credit losses			(157)	(1,724)	(606)
Ending balance	[1]	9,038	11,710	9,038	11,710
Allowance for Loan and Lease Losses, Write-offs		0		0
Allowance for Loan and Lease Loss, Recovery of Bad Debts		0
Provision for Loan and Lease Losses		(210)
Small Business [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		3,338	3,159	2,834	3,508
Charge-offs			(11)	(87)	(59)
Recoveries			33	39	59
Provision for (release of) credit losses			(397)	820	(724)
Ending balance	[1]	3,606	2,784	3,606	2,784
Allowance for Loan and Lease Losses, Write-offs		(59)		(87)
Allowance for Loan and Lease Loss, Recovery of Bad Debts		8
Provision for Loan and Lease Losses		319
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		20,454	18,388	20,973	14,484
Charge-offs			0	0	0
Recoveries			0	0	0
Provision for (release of) credit losses			1,362	492	5,266
Ending balance	[1]	21,465	19,750	21,465	19,750
Allowance for Loan and Lease Losses, Write-offs		0		0
Allowance for Loan and Lease Loss, Recovery of Bad Debts		0
Provision for Loan and Lease Losses		1,011
Home Equity Loan [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		12,428	11,750	11,504	17,986
Charge-offs			(98)	0	(122)
Recoveries			14	26	40
Provision for (release of) credit losses			74	903	(6,164)
Ending balance	[1]	12,433	11,740	12,433	11,740
Allowance for Loan and Lease Losses, Write-offs		0		0
Allowance for Loan and Lease Loss, Recovery of Bad Debts		10
Provision for Loan and Lease Losses		(5)
Consumer - Other [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		533	749	988	740
Charge-offs			(435)	(1,024)	(1,069)
Recoveries			269	474	503
Provision for (release of) credit losses			189	129	598
Ending balance	[1]	567	$ 772	$ 567	$ 772
Allowance for Loan and Lease Losses, Write-offs		(518)
Allowance for Loan and Lease Loss, Recovery of Bad Debts		249
Provision for Loan and Lease Losses		$ 303

[1] Balances of accrued interest receivable excluded from amortized cost and the calculation of allowance for credit losses amounted to $54.0 million and $39.0 million as of June 30, 2023 and June 30, 2022, respectively.